There are known in the art techniques for managing files. For example, when data stored as a file in an auxiliary storage is to be used in a process executed on a computer, the data stored as a file in the auxiliary storage device is read by a main storage device. When a read operation of the data has been completed by the main storage device, the data is written to the auxiliary storage device at a predetermined timing such as at the end of processing. Data that has been read by the main storage device and processed is written as a file in the auxiliary storage device at a determined timing such as at the end of processing. For example, such a technique is disclosed in non-patent document 11. 1 Yamanjo, “Kiso kara Wakaru! PC Nyumon/Sainyumon”, online, searched on 28 Aug. 2013, Internet, <URL:http://yamanjo.net/knowledge/structure/structure_03.html>
When reading and writing of data are performed as described above, two identical items of data, namely, data stored in an auxiliary storage device and data read by a main storage device, exist simultaneously during a period of time in which the data is being used in processing, for example. This causes a reduction in free space in a storage region of an entire storage device in which these items of data, that is, data stored as a file and data stored in a region for executing processing (for example, a storage region in a main storage device that is secured for processing) are stored.